1. Field of the Invention
Embodiments of the invention generally relate to semiconductor processing system, and more particularly, embodiments of the invention relate to a contact electrochemical plating apparatus and method.
2. Description of the Related Art
Metallization of sub-quarter micron sized features is a foundational technology for present and future generations of integrated circuit manufacturing processes. More particularly, in devices such as ultra large scale integration-type devices, i.e., devices having integrated circuits with more than a million logic gates, the multilevel interconnects that lie at the heart of these devices are generally formed by filling high aspect ratio, i.e., greater than about 4:1, interconnect features with a conductive material, such as copper or aluminum. Conventionally, deposition techniques such as chemical vapor deposition (CVD) and physical vapor deposition (PVD) have been used to fill these interconnect features. However, as the interconnect sizes decrease and aspect ratios increase, void-free interconnect feature fill via conventional metallization techniques becomes increasingly difficult. Therefore, plating techniques, i.e., electrochemical plating (ECP) and electroless plating, have emerged as promising processes for void free filling of sub-quarter micron sized high aspect ratio interconnect features in integrated circuit manufacturing processes.
In an ECP process, for example, sub-quarter micron sized high aspect ratio features formed into the surface of a substrate (or a layer deposited thereon) may be efficiently filled with a conductive material, such as copper. ECP plating processes are generally multistage processes, wherein a substrate is prepared for plating, i.e., one or more preplating processes, brought to a plating cell for a plating process, and then the substrate is generally post treated after the plating process. The preplating process generally includes processes such as depositing a barrier/diffusion layer and/or a seed layer on the substrate, precleaning the seed layer and/or substrate surface prior to commencing plating operations, and other preplating operations that are generally known in the art. Once the preplating processes are complete, the substrate is generally transferred to a plating cell where the substrate is contacted with a plating solution and the desired plating layer is deposited on the substrate. Once the plating processes are complete, then the substrate is generally transferred to a post treatment cell, such as a rinse cell, bevel clean cell, drying cell, or other post treatment process cell generally used in the semiconductor art.
However, one challenge associated with conventional plating systems is that it is difficult to provide a uniform plating thickness above both narrow and wide features. For example, conventional plating systems are prone to a characteristic generally termed mounding, which is when the material plated over a substrate having both narrow and wide features accumulates faster or has a greater thickness over the narrow features as compared to the wider features. The result of this characteristic is a buildup or mound of the plated material above the narrow features, which is undesirable for subsequent processing steps, such as chemical mechanical polishing, edge bead removal, electrochemical polishing, and other post plating processes. In response to this challenge, contact-type plating systems have been developed. Contact-type plating systems generally include a pad or membrane in an upper portion of the plating cell, wherein the pad or membrane is configured to contact the plating surface during plating operations. This contact generally operates to minimize mounding characteristics. However, one disadvantage of contact-type plating apparatuses is that it is difficult to obtain sufficient fresh electrolyte flow to the substrate surface as a result of the fluid restriction characteristics generated by the membrane. More particularly, contact-type plating systems generally fail to provide a sufficient flow of fresh electrolyte to the center of the substrate, and as a result thereof, the center of the substrates are generally burned by the plating process.
Therefore, there is a need for a contact-type plating apparatus and method, wherein the apparatus and method are configured to supply sufficient fresh electrolyte to the substrate surface during plating operations to prevent burning characteristics.